In the prior art chairs, the chair is formed mainly by a frame body, a cushion and a back pad. The assembly of these components are performed by studs and screws. However in this prior art structure, the components must be formed with threaded holes or protruded studs for combining these components, or some other screws are used to combine these components. Thereby the manufacturing process is complicated and the assembly work is tedious and time consumed. Thereby it is difficult as the components are to be reused because more works are necessary to detach these components, even it is very often the detaching of the studs and screws cannot be performed so that some components cannot be reused.